Fluids produced from wells typically contain a complex mixture of components including aliphatic hydrocarbons, aromatics, hetero-atomic molecules, anionic and cationic salts, acids, sands, silts and clays. The nature of these fluids combined with the severe conditions of heat, pressure, and turbulence to which they are often subjected, are contributory factors to scale formation, salt formation, paraffin deposition, emulsification (both water-in-oil and oil-in-water), gas hydrate formation, corrosion, asphaltene precipitation and paraffin formation in oil and/or gas production wells and surface equipment. Such conditions, in turn, decrease permeability of the subterranean formation and thus reduce well productivity. In addition, such conditions shorten the lifetime of production equipment. In order to clean deposits from wells and equipment it is necessary to stop the production which is both time-consuming and costly.
Well treatment agents are often used in production wells to prevent the deleterious effects caused by such deposits and precipitates. For instance, scaling in the formation (as well as in production lines downhole) is often controlled by the use of scale inhibitors.
Several methods are known in the art for introducing well treatment agents into production wells. For instance, a liquid well treatment agent may be forced into the formation by application of hydraulic pressure from the surface which forces the treatment agent into the targeted zone. In most cases, such treatments are performed at downhole injection pressures below that of the formation fracture pressure. Alternatively, the delivery method may consist of placing a solid well treatment agent into the producing formation in conjunction with a hydraulic fracturing operation. This method is often preferred because it puts the treatment agent in contact with the fluids contained in the formation before such fluids enter the wellbore where deleterious effects are commonly encountered.
A principal disadvantage of such methods is the difficulty in releasing the well treatment agent into the well over a sustained period of time. As a result, treatments must repeatedly be undertaken to ensure that the requisite level of treatment agent is continuously present in the well. Such treatments result in lost production revenue due to down time.
Treatment methods have therefore been sought for introducing well treatment agents into oil and/or gas wells wherein the treatment agent may be released over a sustained period of time and wherein continuous attention of operators over prolonged periods is unnecessary.
U.S. Pat. Nos. 7,491,682 and 7,493,955 disclose methods of treating a well by use of a composite containing a well treatment agent adsorbed onto high surface area solid carrier materials. Such composites may be used for the slow release of well treatment agents into the formation and the environs. They have been used in various formations including deepwater, tight gas and coal bed methane formations. U.S. Pat. No. 7,686,081 and U.S. Patent Publication No. 2010/0175875 disclose recharging such particles once they are depleted.
Such composites, however, often have an inherent drawback in that they do not exhibit the requisite strength of proppants and thus must usually be mixed at less than 10% by weight of the proppant in the fracture or sand control treatment. Higher loadings result in crushing of the composites translating into a loss of pack conductivity.
There is a need therefore for the development of well treatment composites that exhibit the strength of a proppant and yet are characterized by a high surface area in order that loading of the composite in a proppant pack may be increased.